Received: by 2002:a05:7412:3b8b:b0:fc:a2b0:25d7 with SMTP id nd11csp829730rdb; Fri, 9 Feb 2024 02:24:13 -0800 (PST) X-Forwarded-Encrypted: i=3; AJvYcCUNsK70DJ5IF4eHmVjSsf7DcKCA0fy80JzN6MJ4GgqtAJ/7RYCxqDPhUGcuCdb7b+o6Ed09w0KCRaDI87j70jx9b17r/QbA+6/2+fqYzg== X-Google-Smtp-Source: AGHT+IFIA4Ao1tSFa2pw5gdlsdFXg7O6duXaSeWYa/fGQYrjEToyJOgTGGyL+2BiGLK2KLBwCWoM X-Received: by 2002:a2e:8688:0:b0:2d0:8eff:431e with SMTP id l8-20020a2e8688000000b002d08eff431emr922218lji.44.1707474253539; Fri, 09 Feb 2024 02:24:13 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1707474253; cv=pass; d=google.com; s=arc-20160816; b=DOnHGBXyReGKmfEOgTIXo2ud4mQKbWaWZ+hv8ZCqbTtVFGkX64PAgVINuhJv8D0M7Y c2PeA517frhs/yOuo2NKTTrTea4oX2823WJJrGKCWjYDH9DwAHamq9wzfNh6EHkGZMWJ a7VyOelmzagoO0yplIb0uc4+zAxhKBPC2d2vCa9EfgQIXTO0kwasx++i29KG1F5bitp7 UIce8ZL04a09ZlQ0ckOYRsz2+sjLM/YHwyQ3nuBk9CQYRICRQOUkM8eP0kbp6JAqD7A2 Iy909vrBKsd97jnIE7xH/BBr4Secbg+QnxOS12Wa3KxnmfDDk4e6n7urrp8jM3gBEaTl GI/w== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:from:subject:message-id:references:mime-version :list-unsubscribe:list-subscribe:list-id:precedence:in-reply-to:date :dkim-signature; bh=iC3ltUXDHiI03h8nicKfbM5lCCaHJc2Ye8xyZlGM6ac=; fh=5JUL3uro0XNJ7OQVSnSeWYHfxElzDt+7ew5P1w7lUh8=; b=Ptxn8A51RAi+/PTh6ZSEfmteqDVlnkCCcJoKuB8wzqiZX2WOb3bxru5UV1fiZyBTLw /Eca7i4LB4YNMX0GdVPa6sBFCmipglUT8YTI8dMVouGY5ip/Aza59VLVU0dsvQRwiR6a d6y1Tkny8tTrhbFF8oEDrjUnrf3lXcjEpF6wc+DUQJgiLSW+iQhj1bkRpMkAUHGaJXuQ ZARz5ajmxoFzqwlaWFDX3FRqyPEV0ZABIIZvn7jOK0ZhlLvR6d9FT1EkwwLPdyrj5z+b F3Xsl/uB0fy86Dm6i/9ReXkzDe0FkSdfQX/liDAYBq41SWLeoLV88Cc/5nBCMG05VFjf 9ySQ==; dara=google.com ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=qlVrbZaN; arc=pass (i=1 spf=pass spfdomain=flex--vdonnefort.bounces.google.com dkim=pass dkdomain=google.com dmarc=pass fromdomain=google.com); spf=pass (google.com: domain of linux-kernel+bounces-59216-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) smtp.mailfrom="linux-kernel+bounces-59216-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com X-Forwarded-Encrypted: i=2; AJvYcCUTzYdz2iFBDIFtljznz884XHz5j/DCfOI4/te1cQm9KhdYxQJrdVNFCbypjgExg6yVZwxQW+UOgDrV06YmiBoJJJKMIGO/gG6Vk+7V+g== Return-Path: Received: from am.mirrors.kernel.org (am.mirrors.kernel.org. [147.75.80.249]) by mx.google.com with ESMTPS id z11-20020a05640235cb00b0056065186425si768952edc.29.2024.02.09.02.24.13 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Feb 2024 02:24:13 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-59216-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20230601 header.b=qlVrbZaN; arc=pass (i=1 spf=pass spfdomain=flex--vdonnefort.bounces.google.com dkim=pass dkdomain=google.com dmarc=pass fromdomain=google.com); spf=pass (google.com: domain of linux-kernel+bounces-59216-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) smtp.mailfrom="linux-kernel+bounces-59216-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id 185C41F262CA for ; Fri, 9 Feb 2024 10:24:13 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 742F569DE5; Fri, 9 Feb 2024 10:22:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qlVrbZaN" Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E0AD69D37 for ; Fri, 9 Feb 2024 10:22:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707474142; cv=none; b=O3AuB/EaAEdDcLflP7/HhSzM9JX34NSnrpzAyyE5bU4j1V3ANGIIUUmeRY9lRj8zZbS+tSq0RFZIZEMe8W6MlhSJS2mO/nt12jKNfWphNMOlw8kRus3FwYj1OqQfRJPtvlVSYDjYbO+oKUQ78pX+zlUkJY0DvTOx/AVfNCHl/ok= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707474142; c=relaxed/simple; bh=MApb/KU3APzxlFgZL+OJ5De3oK1aRzd7YLFeINSgGUA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=GzjTLSCDhUIHEQ7xiiJBE48crOJZ9dSfcrYIh/CcUMeCbORIbMMuG24HCiaTzVtu7jPRD2iSjG7QJ62tVZAiKu4w8CboP7e40mLZXBFGadYIZ65jL7mXtLHA2nDNmQoNrBP1R0X3IAZlzpZQQD5+9NL248AZRQTqxMLWrM77nDg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=qlVrbZaN; arc=none smtp.client-ip=209.85.221.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Received: by mail-wr1-f73.google.com with SMTP id ffacd0b85a97d-33b26d4294dso267618f8f.0 for ; Fri, 09 Feb 2024 02:22:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1707474138; x=1708078938; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=iC3ltUXDHiI03h8nicKfbM5lCCaHJc2Ye8xyZlGM6ac=; b=qlVrbZaNchJC2mo5MdWmi/0qD09DVebP+OWYP9yT5z+OVkE+FFmpILE8fjnZhPWT8N UTLvwCNvuOF67sfMj58M1xjUn7sX3/HPuwyNsZsL1xgepuy8/0/vVUL0pXh2hECs6+ea MeLfhj2If8QZoQRs/DO22wZYFzwF3p6a1mrPvlLos4hMpLmr5Q7lNEBkpWvWWJMPWS4x uhSDN6hIp20ctqcTzJ7wX67rDlMAIwU8nG2iyjrm6+c/D3PhQ4uP82+IIN6/UaHJuxHu psJ+HTrTwiKH+9FZd6i080V80TSZHRPEsu0pKP6v4sU5jjEqntCd0NGPC6Qwx9rEYQi1 dSzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707474138; x=1708078938; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=iC3ltUXDHiI03h8nicKfbM5lCCaHJc2Ye8xyZlGM6ac=; b=QCrps9vhz9+QuHJ/Bn6xie7fRvmrO5gLroRq2pYN4rYQZhH/ML9V9KyrmM9CLzFkbq e0AaI1/SujOoyIB9XEkYOvJawadRPjy4y9prlXYlmxhrcw5G6KDY8F1Ow+IydsATTewr pR4u50ZyBSN11W7pZuRpWxz12KK1hbsj2DebEqce8AdlacPidrMFyLZE+J20KdHw5/17 M3rom4CREHlXrl8rnsa14Kls0VD7L07DqQPUHdbpLAbGgYhrKWiogEOcZGCmcnwrnJNg 4qATSA5++K1IwAiLHyxCOQdk/cmtwR1OBUPaC6eeKyOAzhKJlY9KCrqD9Mh+7T3mQjdj g0FQ== X-Forwarded-Encrypted: i=1; AJvYcCVXm3/wgyzBIWV+hiou+59JDae/fW2vs7D5/nadxBxj2vsJNIK1NoOEdSvQt4qrikaJ2C8jW3YgJxt4WqG61oNn00bsvzd0gRbxbvve X-Gm-Message-State: AOJu0Yyyq/JQIDo7W7LF7nPuAXsI4hE8WtzC8NPnMdeCdJTQ4MGzw2BH +qhHbIcAYL5CND9G4VQlGVAPn4A1xc7RYNhqjus3KrSz914H/RgaWhW3aLe/15lMlRj1I4lW2X8 Ve6U9f0uHVkSFXQa7ng== X-Received: from vdonnefort.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:2eea]) (user=vdonnefort job=sendgmr) by 2002:a05:6000:686:b0:33b:316a:10fa with SMTP id bo6-20020a056000068600b0033b316a10famr1719wrb.13.1707474138483; Fri, 09 Feb 2024 02:22:18 -0800 (PST) Date: Fri, 9 Feb 2024 10:21:59 +0000 In-Reply-To: <20240209102202.649049-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240209102202.649049-1-vdonnefort@google.com> X-Mailer: git-send-email 2.43.0.687.g38aa6559b0-goog Message-ID: <20240209102202.649049-4-vdonnefort@google.com> Subject: [PATCH v15 3/6] tracing: Add snapshot refcount From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" When a ring-buffer is memory mapped by user-space, no trace or ring-buffer swap is possible. This means the snapshot feature is mutually exclusive with the memory mapping. Having a refcount on snapshot users will help to know if a mapping is possible or not. Instead of relying on the global trace_types_lock, a new spinlock is introduced to serialize accesses to trace_array->snapshot. This intends to allow access to that variable in a context where the mmap lock is already held. Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2a7c6fd934e9..4ebf4d0bd14c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1300,6 +1300,50 @@ static void free_snapshot(struct trace_array *tr) tr->allocated_snapshot = false; } +static int tracing_arm_snapshot_locked(struct trace_array *tr) +{ + int ret; + + lockdep_assert_held(&trace_types_lock); + + spin_lock(&tr->snapshot_trigger_lock); + if (tr->snapshot == UINT_MAX) { + spin_unlock(&tr->snapshot_trigger_lock); + return -EBUSY; + } + + tr->snapshot++; + spin_unlock(&tr->snapshot_trigger_lock); + + ret = tracing_alloc_snapshot_instance(tr); + if (ret) { + spin_lock(&tr->snapshot_trigger_lock); + tr->snapshot--; + spin_unlock(&tr->snapshot_trigger_lock); + } + + return ret; +} + +int tracing_arm_snapshot(struct trace_array *tr) +{ + int ret; + + mutex_lock(&trace_types_lock); + ret = tracing_arm_snapshot_locked(tr); + mutex_unlock(&trace_types_lock); + + return ret; +} + +void tracing_disarm_snapshot(struct trace_array *tr) +{ + spin_lock(&tr->snapshot_trigger_lock); + if (!WARN_ON(!tr->snapshot)) + tr->snapshot--; + spin_unlock(&tr->snapshot_trigger_lock); +} + /** * tracing_alloc_snapshot - allocate snapshot buffer. * @@ -1373,10 +1417,6 @@ int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, mutex_lock(&trace_types_lock); - ret = tracing_alloc_snapshot_instance(tr); - if (ret) - goto fail_unlock; - if (tr->current_trace->use_max_tr) { ret = -EBUSY; goto fail_unlock; @@ -1395,6 +1435,10 @@ int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, goto fail_unlock; } + ret = tracing_arm_snapshot_locked(tr); + if (ret) + goto fail_unlock; + local_irq_disable(); arch_spin_lock(&tr->max_lock); tr->cond_snapshot = cond_snapshot; @@ -1439,6 +1483,8 @@ int tracing_snapshot_cond_disable(struct trace_array *tr) arch_spin_unlock(&tr->max_lock); local_irq_enable(); + tracing_disarm_snapshot(tr); + return ret; } EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); @@ -1481,6 +1527,7 @@ int tracing_snapshot_cond_disable(struct trace_array *tr) } EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); #define free_snapshot(tr) do { } while (0) +#define tracing_arm_snapshot_locked(tr) ({ -EBUSY; }) #endif /* CONFIG_TRACER_SNAPSHOT */ void tracer_tracing_off(struct trace_array *tr) @@ -6593,11 +6640,12 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) */ synchronize_rcu(); free_snapshot(tr); + tracing_disarm_snapshot(tr); } - if (t->use_max_tr && !tr->allocated_snapshot) { - ret = tracing_alloc_snapshot_instance(tr); - if (ret < 0) + if (t->use_max_tr) { + ret = tracing_arm_snapshot_locked(tr); + if (ret) goto out; } #else @@ -6606,8 +6654,13 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf) if (t->init) { ret = tracer_init(t, tr); - if (ret) + if (ret) { +#ifdef CONFIG_TRACER_MAX_TRACE + if (t->use_max_tr) + tracing_disarm_snapshot(tr); +#endif goto out; + } } tr->current_trace = t; @@ -7709,10 +7762,11 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, if (tr->allocated_snapshot) ret = resize_buffer_duplicate_size(&tr->max_buffer, &tr->array_buffer, iter->cpu_file); - else - ret = tracing_alloc_snapshot_instance(tr); - if (ret < 0) + + ret = tracing_arm_snapshot_locked(tr); + if (ret) break; + /* Now, we're going to swap */ if (iter->cpu_file == RING_BUFFER_ALL_CPUS) { local_irq_disable(); @@ -7722,6 +7776,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, smp_call_function_single(iter->cpu_file, tracing_swap_cpu_buffer, (void *)tr, 1); } + tracing_disarm_snapshot(tr); break; default: if (tr->allocated_snapshot) { @@ -8846,8 +8901,13 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash, ops = param ? &snapshot_count_probe_ops : &snapshot_probe_ops; - if (glob[0] == '!') - return unregister_ftrace_function_probe_func(glob+1, tr, ops); + if (glob[0] == '!') { + ret = unregister_ftrace_function_probe_func(glob+1, tr, ops); + if (!ret) + tracing_disarm_snapshot(tr); + + return ret; + } if (!param) goto out_reg; @@ -8866,12 +8926,13 @@ ftrace_trace_snapshot_callback(struct trace_array *tr, struct ftrace_hash *hash, return ret; out_reg: - ret = tracing_alloc_snapshot_instance(tr); + ret = tracing_arm_snapshot(tr); if (ret < 0) goto out; ret = register_ftrace_function_probe(glob, tr, ops, count); - + if (ret < 0) + tracing_disarm_snapshot(tr); out: return ret < 0 ? ret : 0; } @@ -9678,7 +9739,9 @@ trace_array_create_systems(const char *name, const char *systems) raw_spin_lock_init(&tr->start_lock); tr->max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; - +#ifdef CONFIG_TRCER_MAX_TRACE + spinlock_init(&tr->snapshot_trigger_lock); +#endif tr->current_trace = &nop_trace; INIT_LIST_HEAD(&tr->systems); @@ -10648,7 +10711,9 @@ __init static int tracer_alloc_buffers(void) global_trace.current_trace = &nop_trace; global_trace.max_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; - +#ifdef CONFIG_TRACER_MAX_TRACE + spin_lock_init(&global_trace.snapshot_trigger_lock); +#endif ftrace_init_global_array_ops(&global_trace); init_trace_flags_index(&global_trace); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 00f873910c5d..bd312e9afe25 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -334,8 +334,8 @@ struct trace_array { */ struct array_buffer max_buffer; bool allocated_snapshot; -#endif -#ifdef CONFIG_TRACER_MAX_TRACE + spinlock_t snapshot_trigger_lock; + unsigned int snapshot; unsigned long max_latency; #ifdef CONFIG_FSNOTIFY struct dentry *d_max_latency; @@ -1973,12 +1973,16 @@ static inline void trace_event_eval_update(struct trace_eval_map **map, int len) #ifdef CONFIG_TRACER_SNAPSHOT void tracing_snapshot_instance(struct trace_array *tr); int tracing_alloc_snapshot_instance(struct trace_array *tr); +int tracing_arm_snapshot(struct trace_array *tr); +void tracing_disarm_snapshot(struct trace_array *tr); #else static inline void tracing_snapshot_instance(struct trace_array *tr) { } static inline int tracing_alloc_snapshot_instance(struct trace_array *tr) { return 0; } +static inline int tracing_arm_snapshot(struct trace_array *tr) { return 0; } +static inline void tracing_disarm_snapshot(struct trace_array *tr) { } #endif #ifdef CONFIG_PREEMPT_TRACER diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c index b33c3861fbbb..62e4f58b8671 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -597,20 +597,12 @@ static int register_trigger(char *glob, return ret; } -/** - * unregister_trigger - Generic event_command @unreg implementation - * @glob: The raw string used to register the trigger - * @test: Trigger-specific data used to find the trigger to remove - * @file: The trace_event_file associated with the event - * - * Common implementation for event trigger unregistration. - * - * Usually used directly as the @unreg method in event command - * implementations. +/* + * True if the trigger was found and unregistered, else false. */ -static void unregister_trigger(char *glob, - struct event_trigger_data *test, - struct trace_event_file *file) +static bool try_unregister_trigger(char *glob, + struct event_trigger_data *test, + struct trace_event_file *file) { struct event_trigger_data *data = NULL, *iter; @@ -626,8 +618,32 @@ static void unregister_trigger(char *glob, } } - if (data && data->ops->free) - data->ops->free(data); + if (data) { + if (data->ops->free) + data->ops->free(data); + + return true; + } + + return false; +} + +/** + * unregister_trigger - Generic event_command @unreg implementation + * @glob: The raw string used to register the trigger + * @test: Trigger-specific data used to find the trigger to remove + * @file: The trace_event_file associated with the event + * + * Common implementation for event trigger unregistration. + * + * Usually used directly as the @unreg method in event command + * implementations. + */ +static void unregister_trigger(char *glob, + struct event_trigger_data *test, + struct trace_event_file *file) +{ + try_unregister_trigger(glob, test, file); } /* @@ -1470,7 +1486,7 @@ register_snapshot_trigger(char *glob, struct event_trigger_data *data, struct trace_event_file *file) { - int ret = tracing_alloc_snapshot_instance(file->tr); + int ret = tracing_arm_snapshot(file->tr); if (ret < 0) return ret; @@ -1478,6 +1494,14 @@ register_snapshot_trigger(char *glob, return register_trigger(glob, data, file); } +static void unregister_snapshot_trigger(char *glob, + struct event_trigger_data *data, + struct trace_event_file *file) +{ + if (try_unregister_trigger(glob, data, file)) + tracing_disarm_snapshot(file->tr); +} + static int snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data) { @@ -1510,7 +1534,7 @@ static struct event_command trigger_snapshot_cmd = { .trigger_type = ETT_SNAPSHOT, .parse = event_trigger_parse, .reg = register_snapshot_trigger, - .unreg = unregister_trigger, + .unreg = unregister_snapshot_trigger, .get_trigger_ops = snapshot_get_trigger_ops, .set_filter = set_trigger_filter, }; -- 2.43.0.687.g38aa6559b0-goog